This invention relates to an insulating paste composition for forming ribs in the manufacture of various electronic displays and to a method of rib formation using the composition. More particularly, it relates to an insulating paste composition capable of forming a rib pattern excellent in dimensional precision and crosssectional contour and a method of rib pattern formation using the same.
Production of various electronic displays, such as semiconductor or liquid crystal displays and plasma display panels, generally includes rib formation on a substrate to provide spacers between electrodes or cell partitions. Ribs are formed by, for example, a method comprising applying an insulating paste composition comprising an insulating material, an organic binder and an organic solvent directly to a substrate by screen printing or with a roll coater to form a rib pattern or a method comprising forming a green sheet of the insulating paste composition and transferring the green sheet onto the substrate. However, the conventional rib formation methods involve complicated steps and have great difficulty in forming an excellent rib pattern having rectangular crosssectional contour with high precision. Further, the methods are not suitable for forming a fine line pattern, failing to cope with the latest fine processing techniques. To solve this problem, a lithographic technique has been proposed, which comprises applying an insulating paste composition to a substrate to a desired thickness, forming thereon a pattern mask of a photosensitive resin, and removing the exposed area of the insulating paste composition layer as a protective mask by sandblasting. The problem associated with the known lithographic technique is that, where the insulating paste composition has a high reflectance, the dimensional precision of the lithographically formed pattern mask is adversely affected by the reflection of light at the insulating paste composition at the formation of the photosensitive resin pattern. The ribs formed by the lithographic technique have not only low dimensional precision but a poor crosssectional contour, which are particularly problematical in the production of plasma display panels (hereinafter xe2x80x9cPDPxe2x80x9d) in which white ribs are formed for improving image brightness and have made it difficult to manufacture sufficiently practical PDP.
It has therefore been demanded to develop a method of producing PDP in which a rib pattern having an excellent contour and a high dimensional precision can be formed even with an insulating paste composition containing an insulating material having a high reflectance.
In the light of the above-mentioned circumstances, the present inventors have conducted extensive studies and found as a result that an insulating paste composition containing a light-absorbing substance provides a rib pattern with excellent contour and dimensional precision even where the composition comprises an insulating material having a high reflectance.
An object of the present invention is to provide an insulating paste composition which forms a rib pattern excellent in crosssectional contour and dimensional precision.
Another object of the invention is to provide a convenient method of forming a rib pattern excellent in crosssectional contour and dimensional precision.
The invention provides an insulating paste composition for rib formation which comprises an insulating material, an organic binder, a light-absorbing substance, and an organic solvent. The invention also provides a method of rib formation comprising using the insulating paste composition.
The rib-forming insulating paste composition of the present invention forms a rib-forming layer which prevents irregular reflection from the surface thereof when a photosensitive resin layer provided thereon is irradiated with active rays. As a result, the photosensitive resin layer is allowed to form a resin pattern having a rectangular crosssectional contour. Sandblasting the rib-forming layer using the resin pattern as a mask provides a rib pattern excellent in crosssectional contour and dimensional precision. The composition of the invention is especially effective in the formation of a white rib pattern having a high reflectance. Firing the rib pattern gives sharp and highly precise ribs.
According to the rib formation method of the invention, a rib pattern can be formed easily at a reduced production cost.